Composition-based Reduction of Damping in Fe1-xVx (50nm) Thin Films
L Cheng, H Song, J O. Rantschler, Robert McMichael, William E. Bailey
The reduction of GHz damping a is a critical and unaddressed need in ferromagnetic materials development. Smith has predicted that the signal-to-noise ratios of nanoscale / Ghz spin electronic sensors will be inversely dependent on the free magnetic layer damping a, and independent of GMR/TMR ratio ?R/R, due to ferromagnetic resonance (FMR)-related mag-noise. Techniques to reduce a are virtually unknown, however. Recently materials-based techniques have been developed to tune the magnetization dynamics in ferromagnetic thin films. By adding separate sets of rare-earth dopants, both the damping parameter a and precessional frequency fp of Ni81Fe19 thin films can be increased. Invreases in damping and precessional frequency arise from the introduction of an impurity with higher orbital moment, leading to more efficient transfer of energy into lattice vibrations, or from the introduction of impurity with stronger magnetic anisotropy, stiffening rotations of the magnetization against the lattice. Other studies show that additional damping can be contributed by decoupled magnetic layers through transfer of mobile electrons and their angular momentum. It is not obvious how the introduction of foreign species can be used to reduce the damping of a ferromagnet. A localized moment with lower damping than the host is likely to be ineffective, as the damping would tend towards the host. An effective impurity to reduce the damping would therefore need to change the properties of the host.
Journal of Applied Physics
ferromagnetic materials, magnetic layer damping, nanoscale
, Song, H.
, Rantschler, J.
, McMichael, R.
and Bailey, W.
Composition-based Reduction of Damping in Fe1-xVx (50nm) Thin Films, Journal of Applied Physics
(Accessed June 7, 2023)